Without using a calculator, find the exact value of ∫₂⁰ 4e⁻ˣ(e³ˣ + 1) dx.
- Without using a calculator, find the exact value of ∫₂⁰ 4e⁻ˣ(e³ˣ + 1) dx.[5]
Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- [B1] Rewrite integrand as 4e^(2x) + 4e^(-x)
- [M1] Integrate to obtain form k₁e^(2x) + k₂e^(-x) where k₁ ≠ 4, k₂ ≠ 4
- [A1] Obtain correct 2e^(2x) - 4e^(-x)
- [M1] Apply limits correctly, retaining exactness
- [A1] Obtain 2e⁴ - 4e⁻² + 2 or exact similarly simplified equivalent
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